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- (No Model.)

G. G. SMITH. LEVELING INSTRUMENT.

No. 438,954. Peten ted OotJZl, 1890.

w m n m UNITED STATES PATENT OFFICE.

CHARLES G. SMITH, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR OF ONE-HALF TO HELEN MAR HILL, OF SAME PLACE.

, LEVELlNG-INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 438,954, dated October 21, 1890.

, Application filed February 11, 1890. Serial No. 340,020. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES G. SMITH, a citi zen of the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements strai h -ed es or to an ordinar rectan ular block or beam of wood or other similar material.

The invention is designed as an improvement upon the invention set forth and claimed in Letters Patent granted to me March 30, 1886, No. 338,791.

The invention disclosed in said patent described and illustrated a spirit-level set in a block or beam of wood, which block was provided at one end with vertical and longitu-. dinal passages, a slotted plate closing the-ver-.

tical passage, and a graduated adjustable plate being placed in front of the horizontal passages. A mirror inclined at an angle of forty-five degrees was located at the intersec tion of these two passages, and the horizontal angle between two objects was determined by the ray of light reflected on the mirror through the slot in the plate covering the vertical passage, taken in connection with the aforesaid adjustable graduated plate. This construction was somewhat objectionable, owing to the fact that it was made integral with the beam or block, thus rendering it costly and expensive.

The object of the present invention is to provide an attachment which can be readily applied to and removed from a beam, block, or other similar object; also, to simplify the construction and mode of operation, and generally to improve the implement and render it less costly and complicated.

' The invent-ion consists, essentially, in a sight-tube having horizontal and vertical passages, with oppositely inclined mirrors set at angles of forty-five degrees at the point of intersection of said passages, a slotted plate covering the vertical passage, and the horizontal ends of the tube beveled to form sharp edges, which are coincident with the slots in the plate covering the vertical passage, a downwardly-depending wall and a radially-adjustable plate carrying a' spiritlevel, said plate and the tube being adapted to be secured to a beam or straight-edge, as will be hereinafter more fully explained.

The invention also consists in the novel construction and combinations of parts, hereinafter more fully described and'claimed.

In the accompanying drawings, Figure l is a side elevation of an implement constructed according to my invention applied to a straight-edge. Fig. 2 is a longitudinal section of the same. Fig. 3 is a end view. Fig. 4: is a cross-section. Fig. 5 is a detail View of the sight-plate. Fig. 6 is a detail perspective view of the adjustable plate carrying the spirit-level.

The letter A indicates a beam or oblong formed with straight-edges at its sides, bottom, top, and ends, so that when applied to a building or other structure it will determine the horizontal or vertical linesthereof. To one side of said block is adjustably secured the plate B, carrying the spirit-level C. At its upper end this plate is curved or rounded, forming a housing D, in which the spirit-level is inserted, said housing being closed at one end by a removable cap D. The lower portion of the plate is flat or plane surfaced and is provided with an aperture E, through which passes the screw F, having a milled head G, and by means of which the plate is secured to the block. The upper portion of housing D is provided with a slot H for observing the air-bubble in the spirit-level, and near each end is also provided with a set-screw I,which passes through slots K in a curved protect.

ing-plate L. By loosening these screws the plate L can be slid over the slot H and the glass tube of the spirit-level be protected from injury when the device is not in use, and may be slid back when it is desired to use the device.

For permanently retaining plate B in a vertical or horizontal position I provide the holes B and Biwhich receive the screws 13 which securely hold it.

Mounted upon the upper side of the block A is the sight-tube M, which may be made of metal or other suitable material. The bottom of this tube or frame rests upon the top of block A, and one of its sides is extended or prolonged, forming a depending wall N, having an aperture through which passes the binding-screw F, said wall being interposed and held between plate B and block A. This sight-tube or frame is provided with a vertical passage 0 and two horizontal passages P, said passages intersecting each other, and at their points of intersection R there are located two oppositely-inclined mirrors S S, set at an angle of forty-five degrees. These mirrors meet at their upper ends and are arranged opposite to each other, so that observations may be made from either end of the implement without turning the same.

Closing the upper end of the vertical passage O is an adjustable plate T, having two sight-openings or lateral slots U U, said plate being secured to the tube M by means of setscrews V, by loosening which it may be horizontally adjusted. The ends X of the tube are beveled, as shown, forming sharp edges, the planes of which are coincident with the planes of the sight-openings in plate Tthat is to say, a horizontal line drawn from one of the edges to the other will intersect in the mirrors vertical lines let fall from said sight openings. The tube M is provided at each end with thumb-screws Y, which pass therethrough, and by means of which said tube may be adjusted.

The manner of using the device is as follows: The implement is secured to a beam, block, or straight-edge by placing the lower edge of tube M upon the face thereof and then passing screw F through the apertures in wall N and plate B into the said beam or block. For determining the angular elevation between distant objects the beam or block isplacedor located on one object and the bearings of the distant object taken by elevating one or the other end, as the case may be, of the block or beam until the said object and the edge X of the tube appear in line with each other, as seen through the appropriate sight-opening in plate T. The plate B is now radially adjusted until the air-bubble of the spirit-level indicates level. The angle formed by the spirit-level in this last position and its normal position or true level will be the horizontal angle between said objects. In sighting distant objects and determining the height of the said objects or the distance of the same from the horizontal line passing through the object sighted from the device may be used as in the patent aforesaid-that is to say, a suitable marker, as a pencil, is placed across the face of the object at the proper height, so as to clearly indicate the point by reflection in the mirror, which is determined when the reflection of the object comes in line with the sight-opening in the upper plate and the ends of the tube. Then all that is necessary to determine the level of the objects is to deduct or add the height from the base of the block or beam to the point of the angle of reflection of the mirror, when the common horizontal line of the two objects will be accuratelyobtained. The plate T may also be provided with a central sightopening T, by which distant objects may be accuratelyaligned. Thissight-openingispreferably circular in form, as shown in Fig. 5.

Having thus described my invention, what I claim is- 1. The combination, with a block or beam and an adjustable spirit-level secured thereto, of a sight tube or frame having a vertical passage, horizontal passages intersecting said vertical passage, a top plate having two sight openings therein, and two mirrors oppositely inclined to each other and located at the illtersection of said passages, substantially as described.

2. The combination, with a block or beam and an adjustable spirit-level secured thereto, of a sight tube or frame having a vertical passage, horizontal passages intersecting said vertical passage, a top plate having two sightopenings therein, two mirrors oppositely inclined to each other at angles of forty-five degrees, the beveled lower walls of the hori* zontal passages,and theadj usting-screws passing through the ends of the sight-tube, sub stantially as described.

3. The combination, with the block or beam having a sight-tube, of the adjustable plate B, having its upper end formed into a housing D, having slot H, the spirit-level O, and screw F, substantially as described.

4. The combination, with the block or beam A, provided with a sight-tube, of the adj ustable plate B, having its upper end formed into a housing D, with a slot H, the spiritlevel 0, the curvedplate L, having slots K, the set-screw I, and binding-screw F, substantially as described.

5. The combination, with the block or beam A, provided with a sight-tube having vertical and horizontal passages, the mirrors S S, and a depending wall N, of the adjustable plate 13, having housing D with slot H, the spiritlevel 0, and the screw F for holding plate 13, and wall N, substantially as described.

6. The combination, with the block or beam having a sight-tube, of the adjustable plate 13, having its upper end formed into a housing having a slot H and removable cap D, the spirit-level C, and screw F, substantially as described.

7. The combination, with the block or beam A, provided with a sight-tube having vertical and horizontal passages, the mirrors S S, and a depending wall N, having openings or apertures B of the adjustable plate B, having housing D with slot H and apertures 13,

the spirit-level O, the screw F, and screws B substantially as described.

8. The combination, with the block or beam A, provided with a sight-tube having vertical 5 and horizontal passages and a sight-plate having a central sight-opening T, the mirrors S S, and wall N, of the adjustable plate B,hav- 'ing housing D with slot H, the spirit-level C, and the screw F for holding plate B and wall 10 N, substantially as described.

9. As a new article of manufacture, the herein-described leveling attachment for beams, blocks, straight-edges, and similar objects, the same consisting of asight-tube hav- 15 ing horizontal and vertical passages, with oppositely-inclined mirrors set at angles of forty-five degrees at the point of intersection of said passages, a slotted plateclosing the vertical passage and the horizontal ends of the tube beveled to form sharp edges,'which are coincident with the slots of the said closing-plate, a downwardly-dependingwall, and

CHAS. G. SMITH.

Witnesses:

SAML. C. MILLS, GEO. M. HENAULT. 

